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81.
G. S. BJÖRN 《Physiologia plantarum》1980,48(4):483-485
Abstract
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed. 相似文献
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed. 相似文献
82.
BJÖRN SIGFRIDSSON 《Physiologia plantarum》1980,49(3):320-326
Luminescence and fluorescence were measured at different relative humidities in the lichen Cladonia impexa Harm. Both parameters showed a constant value at relative humidities lower than 80%: thereafter they increased. Low relative humidity was found to decrease energy transfer from chlorophyll b to chlorophyll a. inhibit electron transport, lower electron holding capacity on the reduced side of photosystem two and impair far-red-induced afterglow, reflecting photophosphorylation. In Collema flaccidium Ach. Ach. energy transfer from the accessory pigments phycocyanin and phycoerythrin to chlorophyll a was only possible at high relative humidity. The results are interpreted as due to conformational changes caused by changed water content in the lichen. 相似文献
83.
The polar movement of IAA has been examined in 5-mm root segments of Brassica oleracea and Helianthus annum. The movement was studied partly with IAA-1-14C and partly with IAA-5-3H. In both plants a slight acropetal flux of 14C and IAA-3H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time. A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with in-dole reagent (DMCA). Chromatograms run in isopropanol: ammonia: water, 8:1:1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with Rf 0.4–0.6, probably representing IAA. 相似文献
84.
ASBJØRN FJELD 《Nature: New biology》1971,232(34):238-239
BY ultraviolet irradiation of germiings of the multicellular alga Ulva mutabilis Føyn, it is possible to obtain chimaeric plants which consist of two morphologically different parts of different genetic constitution, one part wild type and the other mutant1, 2. Other plants found have been identical in appearance to the chimaeras, though the morphologically different parts were both genetically wild type. They should be considered phenocopies of the genetic chimaeras. Surprisingly, the genetical chimaeras and their phenocopies were found in equal numbers. This observation and the previous one that only complete mutations are found after ultraviolet irradiation of Ulva cells1, can be explained if only one of the two strands in the DNA molecule is genetically conserved. 相似文献
85.
L. O. BJÖRN 《Physiologia plantarum》1976,37(3):183-184
The protochlorophyll(ide) present in primary roots of dark-grown corn (Zea mays) seedlings has an in vivo absorption maximum at 634 nm. Red light converts the pigment to chlorophyll(ide) a with an absorption maximum at 675 nm. 相似文献
86.
Seasonal and Experimentally Induced Changes in the Ultrastructure of Chloroplasts of Pinus silvestris 总被引:3,自引:0,他引:3
The ultrastructure of chloroplasts in mesophyll cells of Pinus silvesris was examined under the electron microscope. Secondary needles were regularly sampled from a tree in a natural stand for one year. Primary needles from one-year-old seedlings exposed to frost hardening and dehardening conditions in a controlled environment chamber were also studied. These seedlings were exposed to 8 or 55 W m-2. All needles were put in fixative at the different sampling dates and stored in a refrigerator until they were prepared for electron microscopy at the end of the experimental period. During the summer the choroplasts were symmetrically shaped and heavily loaded with starch. The membrane systems were well developed and consisted of both grana and stroma thylakoids. In autumn and during early artificial frost hardening the starch content was reduced, the chloroplasts appeared amoeboid and membrane-free stroma regions were seen. Later the chloroplasts became swollen and aggregated in one part of the cell. Starch was lost and the chloroplasts aggregated earlier at 8 W m-2 than at 55 W m-2. During winter the stroma thylakoids were first reduced in number and later even the grana thylakoids were damaged, resulting in mostly disorganized single membranes. Also the chloroplast envelope disappeared. In spring and early summer the chloroplasts migrated to the proximity of the cell walls. The membrane systems were reorganized and starch accumulated. During the first days of artificial dehardening the photosynthetic membranes were severely damaged, especially at 55 W m-2, but soon new membranes were formed. Starch accumulated earlier at 55 than at 8 W m-2. The reported ultrastructural variations are discussed in relation to functional and biochemical fluctuations caused by the season or by artificial variations in the climate as demonstrated earlier. 相似文献
87.
G. S. BJÖRN 《Physiologia plantarum》1979,46(4):281-286
Phycochrome b, one of the reversibly photochromic pigments found in Tolypothrix distorta seems to exist in only two forms: Pb500 and Pb570. The pigment has been spectroscopically demonstrated in vivo. It has also been separated from other pigments. Two different methods for separation have been used: isoelectric focusing and gel filtration. Preparations of purified phycobilisomes contain phycochrome b. The in vivo and in vitro absorption difference spectra were determined as well as action spectra for the conversions in vitro and in vivo of Pb500 to Pb570 and vice versa. Transformation kinetics of phycochrome b show that the conversions in both directions are initially first-order reactions. 相似文献
88.
Stock plants of pea (Pisum sativum L. cv. Alaska) were grown at different controlled levels of irradiance (4, 16 or 38 W m?2) for 11 days from sowing. Morphactin (CFM, methyl-2-chloro-9-hydroxy-fluorene-9-carboxylate) was applied to the apex of the stock plants 3 days before cuttings were excised. The cuttings were rooted at 16 W m?2. High levels of morphactin (>5 × 10?3 mg l?1) inhibited root formation in the cuttings. Low concentrations of CFM (5 × 10?5 mg l?1) promoted the formation of adventitious roots in cuttings from plants grown at all three levels of irradiance, with the most pronounced effect in cuttings from 4 W m?2. Measurements of ethylene evolution by CFM-treated plants 3 days after application, revealed a stimulatory effect on ethylene production by high CFM concentrations. 相似文献
89.
90.